The oldest landmark of the UNESCO World Heritage Site that includes Stonehenge is not the world-famous stone circle itself, but a long barrow grave. Built around 3650 BC, West Kennet is also one of the largest Neolithic graves to have survived in Britain, reaching a length of 328 feet (100m). Inside, nearly 50 people were buried, as well as a host of grave goods including pottery, beads and tools, before the main passage was blocked off by boulders in around 2000 BC.

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30 of the world's most ancient monuments